Intro to Nutrition Chapter 4
Microvilli contain...
"brush border enzymes" that participate in the digestion of protein and carbohydrates.
What benefits do people gain from being able to detect various tastes? The sense of taste is important because:
-Foods that taste sweet usually contain carbohydrates, major energy sources for cells. -Chemicals that elicit a bitter taste are often poisonous, so people are more likely to eat sweet-tasting foods and reject bitter-tasting ones. -The sour taste can indicate the presence of ascorbic acid, more commonly known as vitamin C. Many people like foods that taste tart or sour, especially when they are included with sweet ingredients. -Sodium stimulates taste buds to detect the salty taste; a food that tastes salty may contain other mineral nutrients as well. -The umami taste is detected when certain amino acids (the "building blocks" of proteins) stimulate taste buds. Foods that elicit the umami taste may be protein-rich.
The pyloric sphincter regulates the passage of chyme through the pylorus at a rate of approximately...
1/2 to 2 teaspoons/minute.
The small intestine has three sections. The first, duodenum, is only about...
10 inches long. Within the duodenum, the acidic stomach contents mix with alkaline fluids secreted by the pancreas and gallbladder. The jejunum is about 3 to 5.5 feet long.
After mixing with gastric juice, the pH of chyme is about...
2.0, which is more acidic than lemon juice or vinegar
Following a meal, the stomach empties in about...
4 hours, but the timing depends on the contents and size of the meal.
Loss of taste can also be a sign of degenerative nerve diseases, such as...
Alzheimer's disease and Parkinson's disease
Parietal
Components that form HCl (hydrogen ions (H+) and chloride ions (CL). Activates pepsinogen, destroys many food-borne microbes.
Osmosis
Each day, about 7.6 to 8.5 quarts (1824 to 2040mL) of water from ingested foods and beverages, as well as the watery secretions of intestinal cells, enter the lumen of the GI tract.
Facilitated diffusion
Enterocytes absorb some nutrients by facilitated diffusion, a process that also does not require energy. Although the nutrient moves down its concentration gradient, it still needs to be carried by a special transport protein within the membrane of the enterocyte. Transport proteins are specific for the type of nutrient they are responsible for carrying. Absorption of the simple sugar fructose occurs by facilitated diffusion
Foods and Beverages Often Eliminated in IBS Diets
Fatty foods, some milk products, drinks that contain alcohol or caffeine, drinks that contain large amounts of artificial sweeteners. Beans, cabbage, cauliflower, and other foods that contribute to intestinal gas.
In addition to heartburn, symptoms of GERD may include nausea, gagging, coughing, or hoarseness. If not treated properly...
GERD irritates the lining of the esophagus and contributes to the development of esophageal ulcers (sores).
The pain results when most of the chyme has left the stomach, and the...
HCl that remains comes in contact with and digests the lining of the mucosa of the organ, forming one or more sores.
Factors that contribute to or worsen GER:
Havin excess body far, especially around the waistline, drinking alcohl and coffee, overeating, eating chocolate, peppermint, and greasy or spicy foods, eating foods that contain tomatoes, smoking or inhaling secondhand smoke.
Crohn's disease and ulcerative colitis are two major types of...
IBD.
Endocytosis
In a few instances, a segment of an absorptive cell's plasma membrane surrounds and "swallows" relatively large substances, such as entire protein molecules. This process enables an infant's intestinal tract to absorb whole proteins in human milk that provide immune benefits. It is not a common way for nutrients to enter enterocytes.
Intestinal bacteria can break down (ferment) undigested food; synthesize vitamins...
K, B-12, thiamin, and biotin that the host may be able to absorb; and produce substances that colon cells can use for energy.
Recommendations to reduce the risk of heartburn
Lose excess body weight, Do not lie down within 3 hours after eating a meal, do not overeat at mealtimes, avoid smoking cigarettes or breathing secondhand smoke, elevate the head of the bed so it is about 6 to 8 inches higher than the foot of the bed, do not wear tight belts or clothes with tight waistbands, learn to recognize foods and beverages that cause heartburn.
Factors that increase the risk of peptic ulcers
NSAIDs, alcohol consumption, genetics smoking, excess stomach acid production
Secretin
Primarily released from the small intestine. Responds to acidic chyme entering the duodenum and first part of jejunum. Stimulates the release of bicarbonate-rich solution from the liver and pancreas.
Cholecytoskinin
Released from the small intestine. Responds to fat and breakdown products of proteins (peptides) entering the snall intestine. Stimulates release of bile from the gallbladder into the small intestine. Stimulates the release of pancreatic enzymes, decreases stomach secretions, and slows stomach motility
Active transport
Some nutrients move from the lumen of the intestine and into an enterocyte against the concentration gradient; that is the concentration of the nutrient is higher inside the absorptive cell than in the lumen. Absorption of these nutrients requires both a unique transport protein and energy. Enterocytes rely on active transport to absorb glucose and amino acids.
Bolus
The mass of food that has been chewed as well as moistened and mixed with saliva
Stomach walls consist of muscle proteins, so how does the stomach avoid digesting itself?
The stomach's mucous cells produce a thick layer of mucus that protects the stomach from being damaged by its acid and digestive enzymes.
In the esophagus, each peristaltic muscular contraction is followed by...
a brief period of muscle relaxation that moves small amounts of food and beverage from the esophagus into the stomach.
People with ulcerative colitis (UC) develop ulcers in the mucosa of the colon and rectum. These sores can spread in...
a continuous pattern from the rectum to the colon, but they do not occur elsewhere in the GI tract.
Bile
a greenish-yellow, bitter-tasting fluid that contains cholesterol, minerals, bile salts, and bilirubin.
Fistulas cause pain and swelling, and often require surgery to repair the abnormality. Additionally, people with Crohn's disease have...
a higher risk of developing cancer of the small intestine and colon than healthy people.
In a living person, the GI tract is...
a hollow, muscular tube that extends approximately over 16 feet in length. The other major component of the digestive system, the accessory organs, assists the functioning of the GI tract.
Gastric glands also have cells (G cells) that secrete gastrin...
a hormone that enters the bloodstream and stimulates stomach motility and the secretory activity of the gastric glands.
Raising the pH of chyme also creates....
a more favorable environment for the activity of pancreatic and intestinal enzymes.
Digestion starts in the mouth (oral cavity). Teeth chew (masticate) food. Mastication is...
a physical activity that prepares solid foods for swallowing and chemical digestion.
An enzyme is..
a protein that speeds up the rate of chemical reaction without being altered in the process.
The wall of the stomach is the thickest and strongest of the GI tract because it has...
a third type of muscle, diagonal (oblique) muscle. By relaxing and contracting, these muscles can mix substances that are within the lumen and control the movement (motility) of the material through the tract.
Within the core of villus is a miniature circulatory system consisting of...
a tiny artery (arteriole), blood capillary network, and vein (venule). The core also contains a lacteal, a vessel of the lymphatic system.
Although many people think heartburn is...
a trivial health problem, frequent chronic gastroesophageal Reflux Disease. Approximately 20% of Americans suffer from GERD, but many of them do not know they have the disease.
Prebiotics are in...
a wide variety of foods, particularly fruits, vegetables, and whole grains. Soybeans, berries, garlic, barley, kale, and legumes are rich sources of prebiotics.
A person with dumping syndrome often experiences...
abdominal fullness, nausea, sweating, rapid heart rate, and weakness not long after eating a meal. These signs and symptoms may be followed with abdominal cramps and diarrhea.
This enormous surface area enables the small intestine to...
absorb nutrients very efficiently.
As a result, the GI tract propels chyme more rapidly through it...
absorbing less water than normal in the process. Increased GI motility also helps the large intestine eliminate the watery feces and the toxic material it contains rapidly.
Under normal circumstances, very little carbohydrate, protein, or fat escape digestion and...
absorption in the small intestine.
A reduction in the number of the...
absorptive cells results in less nutrient absorption, which makes nutrient deficiency disorders more likely.
The liver, gallbladder, and pancreas are...
accessory organs of the gastrointestinal system that play major roles in digestion, even though chyme does not move through them.
The chemical digestion of proteins begins in the stomach. HCl converts inactive pepsinogen into...
active pepsin, which begins the enzymatic digestion of proteins
Physicians detect gastrointestinal ulcers by performing an upper endoscopy. The first step of this procedure involves...
administering a medication that relaxes the patient. After the patient is sedated, the physician inserts a special flexible scope into the person's mouth, down the esophagus, and into the stomach and upper small intestine.
In cases of Crohn's disease, certain immune system cells invade the intestinal lining and cause patches of inflammation. The inflammation can...
affect all layers of the colon as well as the ileum. However, an part of the GI tract, from the mouth to the anus can become inflamed.
The cause of IBS is unknown, but having a history of an intestinal infection, eating certain foods and beverages, and...
after bowel movements, the affected person feels as though his or her elimination of stools was incomplete.
This scale ranges from 0 to 14. A solution with a pH of 7 is neutral; solutions with pH values lower than 7 are acidic, and pH values higher than 7 are...
alkaline (basic).
Proteases digest proteins into their components....
amino acids.
The maximum capacity of the stomach is about 16 cups (380 mL)- the....
amount of food and fluids that an adult may consume during a traditional Thanksgiving dinner, which is followed by dessert.
The disease often results in the formation of intestinal abscesses( infected sores), blockages, and fistulas. An internal fistula is...
an abnormal opening or connection that forms between two regions of the intestinal tract or between a section of the GI tract and an abdominal organ.
During a typical meal....
an adult's stomach can stretch to hold about 4 to 6 cups (960 to 1440mL) of semiliquid material.
Although, saliva also contains lingual lipase, which is...
an enzyme that breaks down fat, the lipase is inactive until it reaches the stomach.
Hemorrhoids
are clusters of small veins in the anal canal. Chronic constipation and straining during bowel movements play a role in the development of inflamed and swollen hemorrhoids. In some cases, the swollen hemorrhoids protrude out of the anus, causing pain, itching, and bleeding.
Probiotics
are live, beneficial microbes (primarily bacteria) that have been grown (cultured) under laboratory conditions.
Certain gastric gland cells synthesize and secrete the primary components of gastric juice, which...
are mucus, hydrochloric acid, intrinsic factor, and digestive enzymes.
Products that contain these microbes are also referred to as probiotics. Many brands of yogurt, for example...
are probiotics because they contain "live and active" cultures of beneficial bacteria.
Diverticula
are small pouches that form in the inner lining of large intestine and push through weak regions of the colon wall. When this occurs, the condition is called diverticulosis
Intestinal sphincters
are thickened regions of circular muscle that function like valves to control the flow of contents at various points in the GI tract.
Lactobacillus and Bifidobacterium
are types of bacteria that are most often used in probiotics. When consumed, adequate amounts of the bacteria must survive the acidic conditions of the stomach and digestive enzymes in the upper small intestine before reaching the large intestine, where they can grow and multiply.
The ability to taste is closely associated with the ability to detect odors; as many...
as 15% of adults have problems with their senses of taste and smell.
Medical researchers do not know what causes diverticula to form. Obesity, physical activity, and cigarette smoking are...
associated with diverticular disease. People with diverticulosis generally do not need to avoid eating nuts or foods with edible seeds. Gradually increasing one's intake of dietary fiber may be helpful, but more studies are needed to clarify whether fiber intake contributes to diverticular disease.
Dehydration can be serious, especially if the vomiting is accompanied by diarrhea. Treatment includes....
avoiding solid food until the condition revolves.
The tongue helps direct the mashed-up food to the...
back of the mouth and into the pharynx ("throat"), where it can be swallowed.
Normally, the LES is closed, preventing the...
backflow of acidic stomach contents into the esophagus/ Heartburn (acid reflux) occurs when the LES fails to close properly
Large numbers of intestinal bacteria eventually become a major component of feces. Interestingly, the composition of the...
bacteria (gut microbiota) varies from person to person due to individual differences, including diet, age environmental conditions, and medication use.
However, not all of the bacteria's metabolic activities are beneficial to health. The...
bacteria can produce potentially harmful products, particularly when they ferment proteins and their components (amino acids). Eating a high-fiber diet, however, appears to reduce the level of protein fermentation in the gut, which may explain some of fiber's healthful benefits.
Dumping syndrome often occurs after surgeries of the esophagus or stomach, including....
bariatric procedures for rapid weight loss.
Not long after eating something toxic drinking too much alcohol, a person may...
begin to feel queasy or "sick to his or her stomach". The individual soon becomes well aware that his or her body has an effective way of removing the harmful food or beverage: vomiting.
Under normal conditions, gut microbiota maintain a balance with each other that...
benefits the health of their human host.
Such ulcers can damage blood vessels in the walls of the esophagus, causing bleeding. Signs of...
bleeding from the esophagus include black, tarlike stools and iron-deficiency anemia. In severe cases, the loss of blood from a bleeding ulcer can be deadly.
If a larger piece of food enters the trachea, it can....
block the windpipe, preventing air from entering the lungs.
Vomiting can also be a response to...
blocked intestines, head injury, rotating movements of the head (motion sickness), hormonal changes in pregnancy, and migraine headaches.
The primary roles of the digestive system are...
breakdown of food into smaller components (nutrients), absorption of nutrients, and elimination of solid waste products.
Nucleases initiate the...
breakdown of nucleic acids (DNA and RNA).
Lysozyme
can destroy some bacteria that are in food or the mouth.
Although stress does not cause peptic ulcers, it...
can worsen them
Mucous cells, secrete mucin, a...
carbohydrate-rich substance that forms mucus when combined with water.
Embedded within the mucosa are...
cells that secrete mucus, a watery slippery fluid.
Lack of dietary fiber, low water intake; anxiety, depression, and other psychological disturbances; and...
changes to typical routines such as taking a long trip or having major surgery, can alter a person's usual pattern f bowel movements.
Mechanical digestion does not change the..
chemical composition of the food, but it facilitates chemical digestion.
IBD is an autoimmune disorder, a...
chronic condition in which the body's immune system does not function properly and begins to attack normal cells.
The dead cells that were shed into the lumen add to the contents of..
chyme and eventually are digested.
The muscular layer has two distinct types of tissue, the...
circular and the longitudinal muscles. The circular muscles are surrounded by the longitudinal muscles.
About half of American adults experience gastroesophageal reflux (GER), which is...
commonly called heartburn or acid refulx.
Water moves freely across the cell membranes of enterocytes because a...
concentration gradient is created by the absorption of water-soluble nutrients such as sugars and minerals.
Following bicarbonate secretion, the...
contents in the small intestine have a pH that is neutral or slightly alkaline- the pH at which the enzymes function best.
Generally, vomiting does not last more than 24 hours. Repeated vomiting, however, can...
deplete body water, resulting in dehydration.
The tip of the tongue, for example, is more likely to...
detect sweet tastes than the sides or back of the tongue, which may explain why people often sample a new food with just the tip of their tongue.
At one time, medical experts thought excessive emotional stress caused peptic ulcers. By the 1990s, however, researchers....
determined that Helicobacter pylori, a type of bacteria that can live in parts of the stomach, was responsible for the development of most stomach ulcers.
Children who suffer from vomiting and/or diarrhea are likely to...
develop dehydration more rapidly than adults who are suffering from these conditions. Signs of dehydration in young children include sunken eyes, dry lips and mouth, and decreased urination
Therefore, treatment of severe diarrhea generally includes...
diarrhea generally includes drinking the replacement fluids that contain sodium, potassium, and simple sugars such as glucose. It is also prudent to acid eating solid foods until the condition resolves.
It's important to not confuse IBS with IBD (inflammatory bowel disease (IBD), which is characterized by chronic inflammation of GI tract. The inflammation causes the typical signs and symptoms of IBD:
diarrhea, rectal bleeding, abdominal cramps, fever, and unintentional weight loss. In some cases, skin rashes or sores, blurry vision, and joint pain also develop.
The alternating pressure exerted by the muscles forces chyme to moves chyme through the...
duodenum, jejunum, and ileum, providing adequate time for maximal nutrient absorption
Such foods often vary among individuals, but...
eating spicy foods tends to worsen ulcer symptoms.
When the small intestine does not have an adequate supply of nutrients for...
energy or cell division, its mucosa cannot replace enterocyte cells.
The residue then moves through the transverse colon, descending colon, and sigmoid colon before...
entering the rectum and finally, the anus.
Water-soluble nutrients and certain fats pass directly from...
enterocytes into the capillary network of the villus.
The digestive system functions in concert with the other organ systems of the body. If the digestive system is not functioning properly, the...
entire body eventually shows signs and symptoms of disease.
Although the actual cause or causes of IBD are unknown, an...
environmental or psychological trigger, such as an infection or a stressful situation, may cause a susceptible person's immune system to function abnormally.
Although lingual lipase becomes active when exposed to the acidic environment of the stomach, the...
enzyme breaks down only 10% of the fat in food. The majority of fat digestion occurs in the small intestine.
This is a critical step in the digestion process because the...
enzymes that function in the small intestine are not active in acidic conditions
People with GERD have a higher risk of...
esophageal cancer than people who do not have a history of the disease.
After being swallowed, the food bolus travels through the...
esophagus, a muscular tube that extends about 10inches from the pharynx to the upper portion of the stomach. The primary function of the esophagus is to transfer a bolus into the stomach.
Prompt treatment of severe diarrhea-within 24 to 48 hours-is...
especially crucial for infants and older adults because they can become dehydrated quickly by the loss of body water.
Intestinal sphincters are also...
essential for normal digestion and absorption because they help control rates of digestion and absorption by keeping the contents within the lumen in place.
While the internal and sphincter is under involuntary control, the...
external anal sphincter that allows feces to be expelled is under voluntary control (delectation).
This fluid lubricates the walls of the small intestine...
facilitating the passage of chyme and protecting the mucosa from being damaged by the material as it moves through the tract.
In many instances, adding more fiber-rich foods to the diet is the...
first step to becoming more "regular."
The liver makes about 2 to 4 cups (480 to 960 mL) of bile daily. Bile...
flows from the liver into the gallbladder via ducts.
Such mechanical activity makes the....
food easier to swallow and increases its surface area, which enables enzymes to have greater access to nutrients.
Loperamide, a medication that is available without a prescription, can be helpful...
for relieving an occasional bout of mild diarrhea. Cases of severe diarrhea, however, require more immediate medical attention.
The main function of the lower portion of the stomach is mixing food with gastric juice to...
form chyme, a semiliquid mass. Chyme leaves the stomach through a canal called the pylorus.
Gut microbiota also metabolize certain phytochemicals (phenols) into...
forms that can be absorbed and used by the body.
Three hormones play key roles in digestion:
gastrin, secretin, and cholecystokinin.
Because a choking person cannot speak or breathe, the victim usually...
grabs his or her throat to indicate there is a problem.
Physicians can also use a colonoscope to introduce the donor's feces into the patient's large intestine. According to the results of many studies...
gut microbiota transplantation is highly effective treatment for case of C-diff infection that are not cured by conventional medical therapies.
As in cases of Crohn's disease, people with UC...
have an increased risk of colon cancer.
In some cases, Crohn's disease causes such extensive destruction of intestinal tissue that the affected person needs to...
have surgery to remove the damaged part. Surgery is not a cure for Crohn's disease because the inflammation eventually develops in other regions of the GI tract.
The FDA has not approved any...
health claims for probiotics.
Changing the types of food eaten (fewer sugary foods), eating smaller meals, and taking certain medications can...
help manage dumping syndrome.
Eventually, these nutrients travel to the liver via the....
hepatic portal vein. Hepatic means "related to the liver."
When a person has an upper respiratory tract infection and the inside of the nose is congested...
his or her favorite foods may seem tasteless and unappealing because the olfactory region is unable to function properly.
When the normal balance is disrupted and fewer species of beneficial bacterial reside in the gut...
inflammation and disease can result.
Salivary amylase
initiates chemical digestion in the mouth. The amylase begins the breakdown of starch
Furthermore, an ulcer may erode through the stomach or...
intestinal wall and allow GI contents to leak into the body cavities, resulting in a potentially life-threatening infection. Therefore, it is important to recognize ulcer symptoms and obtain treatment early.
Parietal cells secrete hydrogen and chloride ions, which form HCL. Parietal cells also synthesize and release....
intrinsic factor, the substance that is necessary for absorbing vitamin B-12.
Segmentation
involves regular contractions of circular intestinal muscles followed by muscular relaxations to mix chyme within a short portion of the small intestine
Gut microbiota transplantation involves...
involves taking some feces from a healthy person and introducing it to the large intestine of the patient. The transfer can be accomplished giving the patient an enema that contains the donor's feces and is retained in the patient's colon for a period of time.
In the US, as may as 15% of the adult population suffers from...
irritable bowel syndrome (IBS), a condition characterized by intestinal cramps and abnormal bowel function, particularly diarrhea, constipation, or alternating episodes of both.
Diarrhea
is a condition characterized by frequent bowel movements and watery stools.
Constipation
is a condition characterized by having fewer than three bowel movements per week or stools that are difficult to eliminate.
Hypogeusia
is a condition characterized by the diminished ability to taste
Dumping syndrome
is a disorder that occurs when a large amount of cyme flows too rapidly into the small intestine.
A peptic ulcer
is a sore that occurs in the lining of stomach or the upper small intestine. The typical symptoms of a peptic ulcer are deep, dull upper abdominal pain and a feeling of fullness that occur about 2 hours after eating.
HCl
is a strong acid that contributes to the low pH of gastric juice.
Bilirubin
is a waste product that results from the breakdown of hemoglobin, the iron-containing pigment in red blood cells.
Saliva
is a watery fluid that contains mucus and a few enzymes, including lysozyme, salivary amylase, and lingual lipase.
As food residue passes through the colon, the material becomes semisolid and...
is called feces and stools. Under normal conditions,75% of feces is water. Most of the remaining solid material consists of bacteria that normally reside in the large intestine and undigested dietary fiber.
gastroesophageal reflux
is characterized by a dull pain or burning sensation generally felt in the upper chest, under the breastbone.
The lower esophageal sphincter (LES), also known as the gastroesophageal sphincter or cardiac sphincter....
is located at the bottom of the esophagus.
Sphincters are located both at the top and bottom of the esophagus. The upper esophageal sphincter....
is not a true sphincter by rather a section of the pharynx that relaxes when a bolus is swallowed, allowing the mass of food to enter the esophagus.
Chemical digestion
is the breakdown of large nutrient molecules in food into smaller components, primarily by the action of stomach acid and various enzymes.
Anosmia
is the complete inability to detect odors. Three percent of American adults have anosmia; the percentage increases with advancing age.
The epiglottis
is the flap of tough tissue that prevents the food from entering the larynx and trachea
Flatulence
is the medical term for expelling intestinal gas.
Digestion
is the process of breaking down large food molecules into nutrients that the body can use.
The pharynx
is the section of the alimentary canal that connects the nasal cavity with the top of the esophagus
Absorption
is the uptake and removal of nutrients from the digestive tract may also be referred to as the gastrointestinal tract (GI tract), alimentary canal, or gut.
The gallbladder concentrates and stores bile until...
it is needed for fat digestion and absorption.
The nutrient moves down its concentration gradient; that is...
it moves from a location where it is more highly concentrated, such as in the lumen , to a place where it is less concentrated, such as inside the absorptive cells. This form of transport does not require the input of energy. The digestive tract absorbs many water-soluble vitamins, lipids, and some minerals by simple diffusion.
The small intestine of a healthy person usually has few microorganisms residing in...
its lumen, particularly in the duodenum and jejunum. In contrast, a healthy large intestine is home to vast numbers of various species (types) of bacteria because of its slower motility and neutral pH.
The upper part of the stomach has tiny gastric glands that are....
lined with specialized cells.
If bacteria or some feces become trapped in the...
little pouches, painful inflammation and infection can occur (diverticulitis).
In solution, these molecules stimulate sensory cells in taste buds that are...
located primarily on the top of the tongue.
Frequent diarrhea can deplete the body's fluid volume, causing dehydration and excessive....
losses of the minerals sodium and potassium.
If the layer of mucus breaks down, HCL and gastric enzymes can...
make contact with the stomach wall, destroying the tissue.
Feces remain in the rectum until muscular contractions move the...
material into the anal canal and then out of the body through the anus.
When a piece of food enters the trachea instead of the esophagus, the...
material irritates the airways and the body responds immediately with vigorous coughing to expel it.
In the past, ulcer patients were advised to consume bland, low-fat diets tat lacked spices to control their ulcer symptoms. Today, a combo of...
medical approaches is used for ulcer therapy. People infected with H. pylori are given antibiotics, as well as medications that reduce stomach acid production. This treatment is highly effective for combating H. pylori infections and healing peptic ulcers.
One end of an enterocyte is exposed to chyme. This end of the cell ("the brush border") has thousands of hairlike projections called...
microvilli that give the tissue a fuzzy appearance when it is viewed under a microscope.
The water and mucus in saliva...
moisten and lubricate food, making it easier and more comfortable to swallow.
Adults should contact a physician if their vomiting lasts for...
more than a day and they have signs of dehydration, such as increased thirst, decreased urination, and dry lips and mouth. Contacting a physician immediately is necessary if there is blood in the vomit (the vomit appears to have coffee grounds in it) or vomiting is accompanied by diarrhea, weakness, confusion, fever, or severe abdominal pain.
Watery meals such as soups spend less time in the stomach; fatty and high-fiber meals spend....
more time there. Obviously, larger meals take longer to empty from the stomach than smaller meals.
Diarrhea occurs when...
more water than normal is secreted into the GI tract or the tract absorbs less water than normal.
Therapy is individualized and may include elimination diets that focus on determining which foods are...
most likely to contribute to IBS symptoms.
Very few individuals are born with a permanent taste disorder....
most taste disorders are temporary and develop as a result of upper respiratory or middle ear infections: radiation treatment; medications such as antibiotics or antihistamines; head injury; or poor dental health.
As fat and partially digested proteins enter the duodenum, the...
mucosa of the small intestine secretes cholecystokinin (CCK). CCK stimulates the gallbladder to contract and release bile into the duodenum.
The wall of the GI tract has distinct layers. The innermost layer, the...
mucosa, surrounds the lumen of the digestive tract, which is a hollow space through which food and fluids pass.
The mucosa of the large intestine has numerous mucus-secreting goblet cells...
mucus is the primary secretion of the large intestine.
Peristalsis is an involuntary response, which means the...
muscular activity happens without the need to think about it.
The cells of the body do not...
need food to carry out their metabolic activities; they need nutrients that are in food.
The combination of medical treatment and lifestyle changes has minimized the...
need for peptic ulcer patients to make drastic dietary changes. Current dietary approaches to treatment include avoiding foods that increase ulcer symptoms.
The dead cells are shed into the lumen, and...
newer absorptive cells constantly replace those that have been sloughed off.
Although diverticulosis is common, most people have...
no signs or symptoms, so they are not aware that they have the disorder.
Additionally, sipping small amounts of water or clear liquids including....
noncarbonated soft drinks such as sports drinks can help prevent dehydration.
Furthermore, constipation can result when a person regularly ignores the...
normal urge to have a bowel movement and avoids making a trip to the bathroom to defecate.
As enterocytes absorb nutrients from chyme, the...
nutrients enter the capillary network or lacteal. Whether a nutrient enters directly into the blood stream of the lymphatic system depends on the type of nutrient.
Simple diffusion
occurs when the concentration of a particular nutrient is higher in the lumen of the small intestine than in an enterocyte.
When antibiotic use kills most of the bacteria in the colon, C-diff is...
often able to survive and multiply. It then secretes toxins that inflame and destroy tissues of the large intestine, causing chronic diarrhea that resists many conventional forms of treatment.
At the base of each villus is the intestinal crypt, the...
opening of a tubular gland.
The entrance to the esophagus is near the larynx ("voice box" and the...
opening of the trachea ("windpipe").
These sensory receptors relay information from the...
oral cavity to a part of the brain that identifies the particular taste.
As a person chews, several salivary glands secrete saliva into the...
oral cavity.
Swift action must be taken to remove the chunk of food from the trachea.....
otherwise the lack of oxygen will cause the person to lose consciousness and die.
Each villus (singular of villi) has an...
outer layer of absorptive cells that are also called enterocytes
In the U.S 60 to 70 million Americans suffer from digestive disorders. Each year...
over 13 million of these individuals are hospitalized because of the disorder, and treating digestive disorders accounts for a significant percentage of all surgical procedures.
Chemists measure the hydrogen ion (H=) concentration of solutions by using the...
pH scale.
As chyme moves out of the ileum and into the large intestine, it...
passes through the ileocecal sphincter. Similar to the pyloric sphincter, the ileocecal sphincter controls the rate at which the contents of the ileum empty the large intestine from following back into the small intestine.
Ageusia
people who have totally lost the sense of taste.
Caregivers should contact a physician if the child has vomiting and diarrhea that...
persist for more than a few hours and shows signs of dehydration.
Loose stools are often accompanied with mucus, and after bowel movements, the affected...
person feels as though his or her elimination of stools was incomplete. For reasons that are unclear, women are more likely than men to suffer from IBS.
The digestive tract breaks down food by...
physical and chemical processes.
Mechanical digestion refers to...
physical treatments that food undergoes while it is in the intestinal tract, such as being chewed into smaller pieces and mixed with various secretions.
Probiotics are also available in...
pills (dietary supplements).
Little additional absorption, other than of some water and minerals, takes...
place in the large intestine because its mucosa has no villi.
A person's risk of developing heart disease, certain chronic intestinal and liver diseases, and...
possibly, obesity has been linked to the diversity of his of her intestinal bacteria.
Scientists are studying the roles that gut microbiota play in the...
prevention and treatment of certain infectious and inflammatory diseases.
Most digestion and nutrient absorption occurs in the upper part of the small intestine...
primarily in the duodenum and upper jejunum. The last portion of the small intestine, the ileum is about 5 to 9 feet long.
The small intestine is the...
primary site for nutrient digestion and absorption
The salivary glands of a healthy person can...
produce about 4 to 6 cups (960 to 1440 mL) of saliva each day
As a result of their metabolic activity, intestinal bacteria also...
produce gases that may be expelled through the anus.
The pancreas is an accessory organ of the digestive tract that...
produces and secretes many of the enzymes that break down carbohydrates, protein, and fat in the GI tract.
Recall that bile is necessary for...
proper fat digestion and absorption. CCK also triggers the release of enzyme-rich pancreatic juice into the small intestine. Another action of CCK is reducing gastric secretions, and motility, thus, helping to control the flow of chyme from the stomach. As a result, nutrient digestion and absorption can proceed at a reasonable rate within the small intestine.
People suffering from GERD should ask their physicians to...
recommend other medications that are taken daily to inhibit stomach acid production, preventing heartburn.
In some cases, blood vessels near diverticula become damaged, causing...
rectal bleeding. Antibiotics and, sometimes, surgery may be necessary to treat diverticulitis.
Although taste buds that can detect each kind of taste are distributed all over the tongue, some....
regions of the tongue are more sensitive to one type of taste and less sensitive to the others.
Secretin stimulates the pancreas and liver to...
release a bicarbonate-rich solution that raises the pH level of chyme. As a result, the mucosa of the small intestine is protected from the potentially harmful effects of HCl.
Gastrin
released from the stomach. Responds to food entering the stomach. Triggers parietal cells to release HCl and chief cells to release pepsinogen. Stimulates stomach and small intestinal motility
In addition to enzyme activity and peristalsis, the small intestine also...
relies on segmentation to facilitate digestion
Taking over-the counter antacids can neutralize excess stomach acid and...
relieve the discomfort of heartburn within minutes, but these products do not prevent heartburn.
The scope also enables the physician to use tools to treat areas of bleeding or...
remove pieces of tissue (biopsy) for microscopic examination.
Surgery is often necessary to...
remove troublesome hemorrhoids.
The use of fecal transplants may also benefit people with chronic intestinal disorders, especially ulcerative colitis or Crohn's disease. The FDA however...
requires physicians to obtain a permit to use gut microbiota transplantation to treat diseases other than resistant C-diff infections.
As is often the case, more...
research is needed to determine the long-term safety and effectiveness of gut microbiota transplantation
When a sphincter contracts, it closes the passageway and...
restricts the flow at that point in the digestive tract.
Chief cells x 2
secretes gastric lipase. Digests protein after conversion to pepsin.
G cell
secretes gastrin. Functions stimulates stomach motility and gastric gland activity.
Parietal x2
secretes intrinsic factor. Functions to facilitates the absorption of vitamin B-12
Muc0us function
secretes mucus. protects stomach mucosa from HCL and enzymes
Chief cells
secretes pepsinogen. Digests protein after conversion to pepsin.
"Abdominal thrusts" (Heimlich maneuver) are a...
simple and effective first-aid technique that can dislodge a piece of food or other item from the trachea.
If the affected person is able to retain...
small amounts of fluid, then he or she can try to drink increasing amounts of fluid until the vomiting subsides completely.
The process of absorbing nutrients across the wall of the...
small intestine depends on several factors, including the type and amount of the nutrient.
Any remaining water and the undigested material that reach the end of the...
small intestine must pass through the ileocecal sphincter before entering the large intestine.
The rapid cellular turnover rate of the....
small-intestinal mucosa leads to relatively high nutrient needs for these tissues.
Additionally, the pancreas secretes bicarbonate ions (HCO3-). The pH of chyme is approximately 8.5...
so the juice neutralizes the highly acidic chyme when it enters the duodenum.
When a person talks, the larynx is not covered by the epiglottis....
so the trachea also remains open.
Chief cells secrete gastric lipase and...
some chemically inactive digestive enzymes, particularly pepsinogen.
The churning movements mix food with gastric juice, and as a result...
some protein and fat in the chyme break down. Although the stomach absorbs very few nutrients from chyme, a few drugs, including some aspirin and alcohol, can pass through the organ's walls and enter the bloodstream.
Such destruction can cause one or more...
sores (gastric or peptic ulcers) to form.
Hormones are chemical messengers that convey information to cells (target cells). Target cells have...
special receptors on their cell membranes that enable them to respond to a hormonal signal.
Olfactory bulbs
specialized structures in the brain combines information about the smell of foods with taste sensations from the mouth to identify the food's
The sense of smell (olfaction) contributes to the ability to taste food. As food is chewed, it releases chemicals that become airborne and...
stimulate the olfactory region of the nasal passages. This region signals the olfactory bulbs.
The enzymatic digestion of starch that began in the mouth stops in the....
stomach because salivary amylase does not function when the pH is lower than 4.5.
When stimulated by the presence of food, the...
stomach's muscular walls respond by producing waves of peristalsis.
After a bolus passes through the LES, it enters the...
stomach, a muscular sac that stores and mixes food.
Treatment of IBS may include learning...
stress management strategies, obtaining psychological counseling, and taking antidepressant and other medications.
There may be a sixth sense of taste. Scientists are...
studying the possibility that human taste buds can also detect certain fats in foods.
A person's diet influences the kinds of bacteria that make up his or her gut microbiota. Prebiotics are...
substances in food that are poorly digested by humans but support and promote the growth of probiotics in the colon.
H. pylori infection makes the lining of the stomach more...
susceptible to being damaged by stomach acid. In addition to infection with H. pylori, other factors are associated with the development of peptic ulcers, particularly smoking cigarettes, heavy consumption of alcohol, and regular use of NSAIDS (nonsteroidal anti-inflammatory drugs) such as aspirin, ibuprofen, and naproxen.
Taste buds have specialized cells that help to distinguish five basic tastes:
sweet, sour, salty, bitter, and the savory or umami taste.
The liver processes and stores many nutrients. This organ also...
synthesizes cholesterol and uses this type of lipid to make bile.
Probiotics may help prevent the diarrhea that often occurs when antibiotics are...
taken and may be useful in treating people with irritable bowel syndrome. However, reliable scientific evidence about the long-term safety and effectiveness of using probiotics is lacking.
The brain combines information about the smell of foods with...
taste sensations from the mouth to identify the food's flavors.
In addition to playing an important role in digestion, the mouth senses...
taste, temperature, and texture of foods. When food comes in contact with saliva, certain molecules in the food dissolve.
The accessory organs contain the...
teeth, tongue, salivary glands, liver, gallbladder, and pancreas.
In adults, diarrhea that is accompanied by bloody stools or lasts more...
than 7 days may be a sign of a serious intestinal disease, and a physician should be consulted.
The pyloric sphincter
that surrounds the pylorus regulates the flow of chyme into the small intestine.
The digestive system has two major components
the GI tract and accessory organs.
When swallowing initiates, breathing automatically stops, and...
the bolus normally lands on the epiglottis, making it cover the opening of the larynx. These responses keep swallowed food from entering the trachea, which would lead to choking.
No special diets are used to treat IBD. However, people with...
the conditions often find that certain foods seem to trigger flares, so they learn to avoid those items. Physicians generally prescribe medications to control IBD, but surgery may be necessary, especially in cases that do not respond to drug treatment.
The small intestine is the major site of chemical and mechanical digestion of nutrients. Most digestion occurs in...
the duodenum and upper part of the jejunum.
Most cases of diarrhea result from bacterial or viral infections of...
the intestinal tract. These bacteria or viruses produce irritating or toxic substances that increase the motility of the GI tract.
The small intestine is a coiled, hollow tube that extends from the stomach to the large intestine. The small intestine is...
the longest component of the GI tract. The small intestine is "small" because the tube's diameter is only about 1 inch, approximately half the width of the large intestine.
When acidic chyme passes through the pyloric sphincter and enters the duodenum, cells in..
the mucosa of the duodenum and first part of the jejunum release secretin.
Researchers are investigating the role of...
the nervous system in stimulating these abnormal movements of these abnormal movements of the intestinal tract.
While chyme passes through the lumen of the small intestine, enzymes secreted by...
the pancreas and mucosa of the small intesting break down large nutrient molecules in the mass, as well as mucosal cells that have been shed into the lumen.
When an intestinal sphincter relaxes...
the passageway opens and the contents of the GI tract flow through it.
Heartburn is not...
the result of a heart problem but is caused by the passage of acidic contents from the stomach into the esophagus.
People with IBD typically experience "flares" periods in which...
the signs and symptoms of the disease occur, followed by periods of remission in which they are relatively healthy.
Although vomiting is an unpleasant experience, it prevents toxic substances from entering...
the small intestine, where they can do more harm or be absorbed.
The large intestine is about 5 feet (1.5 meters) long and has a larger diameter than...
the small intestine.
When food enters the stomach, G cells in...
the stomach's gastric glands secrete gastrin. Gastrin also stimulates the motility of the stomach and small intestine, and signals the ileocecal sphincter between the small and large intestines to relax.
Food spends a relatively short amount of time in the oral cavity, compared to....
the time it spends in the stomach and small intestine. Therefore, only a small amount of food breakdown occurs in the mouth.
Water, cholesterol, minerals, and most vitamins do not need to undergo digestion, so...
they are absorbed intact.
Most lipids must undergo special processing within enterocytes before...
they enter lacteals. By the time chyme reaches the middle part of the ileum, most of its nutrient contents have been digested and absorbed. It takes about 3 to 5 hours for chyme to move from the duodenum to the end of the ileum.
Enterocytes develop in the bottom of the crypt, and as...
they mature, they move to the tip of the villus. Absorptive cells live for only 3 to 6 days.
Vomiting occurs when the vomiting center in the brain interprets info from various nervous system receptors, including...
those concerned with the physical and chemical conditions of the stomach, small intestine, and bloodstream. When the center detects a toxic chemical, it initiates vomiting by contracting the abdominal muscles, expelling the contents of the stomach and duodenum forcefully out of the body via the mouth.
Obstruction of the nasal passageways; brain tumors; dental disease; and irritation of the inner lining of the nose due to the common cold or nasal allergies contribute...
to the partial or total loss of the sense of smell.
After moving through the ileocecal sphincter, unabsorbed water and....
undigested remains of chyme ("food residue") enter the cecum and then the ascending colon in the right side of the abdomen.
For reasons that are unclear, women are more likely than men to suffer from IBS. The cause of IBS is...
unknown, but having a history of an intestinal infection, eating certain foods and beverages, and experiencing emotional stress are associated with the disorder.
It is not unusual for the sores to damage the wall of a blood vessels, causing bleeding; thus...
untreated peptic ulcers may result in iron-deficiency anemia.
C-diff bacteria are...
unusual but potentially harmful resident of the colon. The growth is normally kept in check by the beneficial populations of gut bacteria.
The scope is equipped with a video camera that transmits images of the lining of the esophagus, stomach, and...
upper small intestine to a screen that the physician views for the presence of ulcers, eroded areas, or cancerous tumors.
People should wait about 3 hours after meals before lying down because remaining...
upright reduces the likelihood that stomach contents will push against the lower gastroesophageal sphincter and move into the esophagus.
Starvation, antibiotic use, and excessive emotional stress are among the factors that can....
upset the normal balance and diversity of bacterial populations in the GI tract.
Currently, researchers are testing the safety and effectiveness of...
using gut microbiota transplantation (GMT), commonly referred to as "fecal transplantation, " to treat certain intestinal disorders, such as Clostridium difficile infection.
The mucosa of the small intestine is highly folded and covered by tiny, fingerlike projections called...
villi. The villi and folds provide a healthy mucosa with a surface area of about 200 square meters, the size of regulation, singles tennis court.
A healthy body absorbs most of the...
water that enters the GI tract
Most digestive enzymes are hydrolytic, which means they require...
water. Lipases are hydrolytic enzymes that help break down fats into smaller molecules (lipo refers to "fat").
To accomplish digestion, the small intestine secretes approximately 1 1/2 quarts of...
watery fluids that contain mucus and enzymes each day.
The act of swallowing signals the GI tract that food is being eaten and stimulates peristalsis,...
waves of muscular contractions that help move the material through most of the digestive tract.
Individuals who feel uncomfortable because their bowel habits have changed and....
who have hard, dry feces that are difficult to eliminate should discuss the matter with a physician.